EMI spring configuration

ABSTRACT

An electromagnetic shield system for cartridge-based printed circuit cards inserted into a printed circuit mother board comprises a card level system and a board level system which are electrically connected upon card insertion to provide more effective EMI shielding system. Prongs on a card level tab provide continuous EMI shielding even as card insertion operations are taking place. The principal linkage between the card level and board level systems is provided by a flexible shield strip which mates with apertures in a conductive board stiffener and simultaneously contacts not only a conductive cartridge bezel, but also contacts an EMI shield plate disposed on the printed circuit card.

[0001] This application is a divisional of U.S. patent application Ser.No. 09/941,809 filed on Aug. 29, 2001, entitled “EMI SpringConfiguration”, the entirety of which is hereby incorporated herein byreference.

BACKGROUND OF THE INVENTION

[0002] The present invention is generally directed to a system, method,and apparatus for packaging electronic circuit components. Moreparticularly, the present invention is directed to a system forelectronic component packaging which permits easy insertion and removalof fully populated circuit boards without having to remove printedcircuit cards which have already been inserted into the boards. Evenmore particularly, the present invention is directed to systems,methods, and devices which enhance the ability to package electroniccomponents in a dense manner while still being able to provide not onlyair cooling but which also provides an effective system forelectromagnetic interference (EMI) shielding.

[0003] It should be appreciated that not all of the features of thepresent invention need to be incorporated into a single device orsystem. Many of the features found in the present invention may beemployed independently from one another. In general, the presentinvention seeks to solve a number of problems with respect to electroniccircuit packaging. In particular, it is desirable to employ printedcircuit cards which can be easily inserted and removed from printedcircuit boards without the removal of the board and without removal ofany cabinet or enclosure surrounding the electronics package. In desiredembodiments of the present invention, therefore, it is found thatprinted circuit cards are capable of being “hot plugged” into a printedcircuit board.

[0004] Additionally, it is noted that, in preferred embodiments of thepresent invention, circuit components operate at relatively highfrequencies. At higher frequencies, problems associated with thepropagation of electromagnetic interference become more significant.Accordingly, for those situations in which higher frequency componentsare desired, there is a correspondingly higher desire to employelectromagnetic shielding systems. Thus, there should be provided amechanism for providing EMI shielding that is commensurate with thenotions of hot pluggability. In other words, the EMI shielding systemshould be compatible with the notion that printed circuit cards areremoved and inserted from printed circuit boards which are themselvesnot pluggable.

[0005] Hot pluggable systems are shown in U.S. Pat. No. 6,062,894 issuedMay 16, 2000, and assigned to the same assignee as the presentinvention. However, in the system described therein, there is adependence on the existence of an external cabinet to effect thevertical motion of the printed circuit card into a corresponding matingsocket on a printed circuit board. The presence of physical contactbetween the mechanism for insertion and removal and an enclosure whichsurrounds a printed circuit board precludes the use of such devices inmechanisms for which the entire printed circuit board itself isremovable.

[0006] It is also noted that the present discussion refers to printedcircuit boards and printed circuit cards. As contemplated herein, theprinted circuit board is the larger component into which at least oneprinted circuit card is inserted for purposes of electrical connection.The present invention places no specific limits on either the size of aprinted circuit board or the size of a printed circuit card. In the mostgeneral situation, a circuit board is populated with a plurality ofprinted circuit cards. That is, the printed board has a number ofprinted circuit cards inserted therein. Accordingly, as used herein, theterms “printed circuit board” and “printed circuit card” are consideredto be relative terms. However, it is also noted that one of themotivating factors in the design of the present invention is the factthat printed circuit boards are, when fully populated, relatively heavyand possess one or more connectors at the edges thereof. These boardedge connectors typically possess a large number of electricalconnections to accommodate the correspondingly larger number ofelectrical connections that must be accommodated for a board which ispopulated with a number of printed circuit cards. The present inventorshave also contemplated a mechanism for insertion of the entire board ina tight space without the necessity of removing any of the printedcircuit cards. Accordingly, some of the specific situations contemplatedby the present inventors have also resulted in the inclusion ofmechanisms for insertion and removal of fully populated printed circuitboards.

[0007] Normally the circuit board, the mother board if you will, isconsidered fixed and does not usually constitute a movable structure.Moreover, even in those circumstances where one might contemplateinserting or removing a circuit board, one would normally not considersuch an operation without first removing the printed circuit cards fromthe board. Because a typical printed circuit board is often populatedwith a relatively large number of printed circuit cards, the size andweight of the circuit board is typically relatively large. Thus, one isnormally presented with the problem of moving (in forward and reversedirections) a large, flat, relatively thin substrate. Particularlyduring insertion operations, such a physical structure is likely toexperience bending and flexing motions typically referred to as “oilcanning.” Accordingly, solutions to problems in the present art addressthis issue as well.

[0008] Accordingly, the present inventors are presented with thefollowing sometimes competing packaging problems: oil canning, dense andclose packaging, air cooling, electromagnetic interference shielding,hot pluggability, the desire to provide an easy to load cartridge forcarrying printed circuit cards, mechanisms requiring a mechanicaladvantage for insertion and removal of entire circuit boards, theremoval of fully populated boards and the insertion thereof, and meansto provide a cooperative EMI shielding arrangement in a system whichprovides circuit board guide mechanisms which do not require physicalcontact with a surrounding enclosure or cabinet.

SUMMARY OF THE INVENTION

[0009] In accordance with a preferred embodiment of the presentinvention, a number of features are provided which together solve all ofthe competing problems indicated above. In particular, a significantaspect of the present invention is provision of a docking cartridgewhich serves as a printed circuit card carrier and which is capable, inand of itself, of inserting and removing electronic printed circuitcards. While the present invention is particularly suitable for theincorporation of printed circuit cards meeting the so-called PCI(Personal Computer Interface) Standard, the principles of the presentinvention are generally applicable to any printed circuit card having anedge connector which is insertable into a corresponding mating connectoron a printed circuit board. The docking cartridge of the presentinvention includes an actuating mechanism for card insertion which iscompletely self contained and which does not rely upon any physicalcontact with an enclosure or cabinet. Rather, the docking cartridge ofthe present invention interacts with a single-sided cartridge guidemechanism which is provided at the printed circuit board level.Moreover, the docking cartridge of the present invention is providedwith an easy load mechanism for the printed circuit card. In particular,the docking cartridge is provided with a front bezel which alsoconstitutes part of an EMI shield mechanism and which is also pivotablewith respect to a top cartridge wall structure. The top cartridge memberis slidably disposed with respect to a circuit card carrier whichcontains corner clips and slidable adjustable mechanisms as shown in theaforementioned U.S. Pat. No. 6,062,894. The top member is thus slidablyattached to a moveable carrier which moves the printed circuit board upand down so as to provide insertion and removal of the circuit boardwith respect to mating electrical connectors on the printed circuitboard.

[0010] A front bezel of the docking cartridge is also provided with amechanism for ensuring EMI shielding during the entire insertion andremoval process. In particular, desirable circuit boards for use inconnection with the present invention include a front EMI shield platewhich has electrical contact with the front docking cartridge bezel. Inparticular, such desirable printed circuit cards having this plate alsoinclude, on the bottom of this shield plate, a tab portion which engagesa flexible EMI shield strip which is disposed on an electricallyconductive stiffener which provides protection against theaforementioned oil-canning effect and which furthermore provides its owndegree of EMI shielding for board level circuits and components. The EMIshield strip used in the present invention possesses a geometricstructure which renders it readily capable of being fabricated instamping and forming operations. This EMI strip is disposed so that itincludes slotted opening portions which engage edges of apertures foundin parallel rows in the stiffener. The strip engages these apertures inone row and includes a flexible portion which extends into the openingin a parallel row of stiffener apertures. Thus, in accordance with thepresent invention, as the printed circuit is inserted into the printedcircuit boards so as to make electrical contact with circuits on theboard, there is also provided a continuous EMI shield as the tab on theprinted circuit card engages a flexible tab portion on the EMI stripwhich is in electrical contact with the conductive stiffener.

[0011] One of the other significant problems addressed by the presentinvention is the fact that a fully populated circuit board is relativelyheavy and typically possesses a large number of electrical circuitcontacts thus increasing the force needed to provide proper electricalconnection. The mechanism for providing this force should not besignificantly large nor should it consume significant amounts of space.That is to say, the mechanism for inserting and removing the circuitboard should be compact and consistent with the compact and densepackaging notions of the present invention. Furthermore, this mechanismshould be compatible with the other structures provided herein, notably,the stiffener and the EMI shielding system.

[0012] The present invention incorporates two principle aspects. A firststructural component utilizes an independent, self-contained cartridgefor containing printed circuit cards intended for insertion into andremoval from tight spaces. A second aspect of the present inventionincludes the structure of a printed circuit board which is usable inconjunction with the aforementioned cartridges. Furthermore, thecartridge and board system of the present invention cooperativelyinteract to provide EMI shielding mechanisms not only compatible withthe easy insertion and removal of circuit cards, but which also providea cooperative mechanism for the insertion and removal of an entirecircuit board in its fully populated state, that is, with all printedcircuit cards inserted and connected.

[0013] With respect to the first aspect of the present invention whichrelates to the cartridge for protecting, transporting, inserting, andthe removal of printed circuit cards, it is noted that this cartridgeincludes three main components: a front bezel, a top cartridge wallmember, and a movable carrier which is upwardly and downwardly movablewith respect to the bezel and the top cartridge wall. The cartridge alsoincludes a lever actuated mechanism attached to the top of the bezelwhich provides sufficient force for card insertion. The lever actuatedmechanism of the cartridge is disposed in such a way as to provide bothupward and downward forces to the movable carrier at a point along thecarrier which is appropriate for both short and long printed circuitcards. The cartridge of the present invention also includes a sidecover. In preferred embodiments of the present invention, the bezel ismetal and is in continuous electrical contact with an EMI shield platefound on certain printed circuit cards which are desirably useful inconjunction with preferred embodiments of the present inventionparticularly when they operate at relatively high frequencies. Theseshield plates preferably include a lower tab portion which extendsthrough an opening in the bottom of the front bezel and which engages anEMI shield spring which thus allows it to be electrically connected witha conductive stiffener affixed to the printed circuit board.

[0014] With respect to the second aspect of the present invention whichrelates to the printed circuit board itself, the board is provided withan electrically conductive shield and stiffener as mentioned above withrespect to the incorporation of the tab and spring structures.Furthermore, printed circuit boards of the present invention include anonconductive base member which is disposed on a side of the printedcircuit board opposite the stiffener. This base support structureprovides additional resistance to “oil canning” effects that can occurparticularly in larger printed circuit board structures. The printedcircuit board also includes special guides disposed at the printedcircuit board level. These guides engage ridges disposed on side wallcovers for the printed circuit card cartridges, as described above. Aparticular feature of the cartridges also includes a mechanism forinterlocking adjacent cartridges. Accordingly, a desirable aspect of thepresent invention is the fact that the special guides employed herein donot require slot and ridge structures to be present on both sides of theinserted cartridge. This is significant in the present invention sincethis feature permits cards to be made thinner and accordingly increasesthe overall packaging density which, as described above, is a highlydesirable aspect of the present invention.

[0015] The stiffener employed in conjunction with the printed circuitboard includes a front row of parallel slots which are spaced to receivean EMI spring shield structure which cooperates with the cartridgestructure to provide a continuous EMI shield. Additionally, the presentinvention also includes a force-producing mechanism which is capable ofproviding a significant mechanical advantage for insertion and removalof the printed circuit board itself, even when requiring all of theboard edge connectors to be mated with corresponding off-boardconnectors. In preferred embodiments of the present invention, theinsertion and removal mechanism for the printed circuit board includes atoothed arm which engages a wrench-activated pinion gear which isaffixed to the above-mentioned stiffener at the front or leading edge ofthe printed circuit board. The toothed arm is pivotally connected toforce-producing arms which include pins which ride in slots in the basestructure which supports the printed circuit board from below. As thepinion gear is rotated, the combination of the toothed arm and theforce-providing levers changes to and from a “T” and “Y” shape. Thus, asthe pinion gear is rotated, the lever arms move in what is bestdescribed as a “backstroke” motion. These levers push against cabinet orenclosure pins and, in doing so, cause the insertion or removal of thecircuit board, in its entirety, into or out of a mating electricalconnector.

[0016] The cartridge of the present invention is also constructed insuch a manner so as to employ components which are pivotally connectedso as to enable easy insertion of printed circuit cards having variousdimensions. In effect, the maximum size of a card employed in thepresent invention is thus determined by the height of the bezel and thelength of the cartridge top.

[0017] Accordingly, it is an object of the present invention to providea system for packaging electronic circuit components in tight spaces.

[0018] It is also an object of the present invention to provide anapparatus for inserting and removing printed circuit cards in tightquarters.

[0019] It is a still further object of the present invention to providea cartridge which is capable of transporting, protecting, inserting, andremoving printed circuit cards in a self-contained manner.

[0020] It is also an object of the present invention to providemechanisms which support hot pluggability of electronic circuit cardsand boards.

[0021] It is a still further object of the present invention to providea mechanism which permits insertion and removal of fully populatedelectronic circuit boards.

[0022] It is also an object of the present invention to provide acartridge, for containing printed circuit cards, which is easilyloadable.

[0023] It is furthermore an object of the present invention to provide asystem in which continuous EMI shielding is provided between an easilyremovable printed circuit cartridge and a printed circuit board.

[0024] It is yet another object of the present invention to provide acartridge for printed circuit cards which is readily adapted to holdcards of varying sizes.

[0025] It is yet another object of the present invention to provide asystem of interlocked printed circuit card cartridges and a supportingprinted circuit board.

[0026] It is yet another object of the present invention to provide amechanism by which an entire fully populated printed circuit board isreadily inserted into and removed from the system in which it iselectrically connected.

[0027] It is also an object of the present invention to provide aprinted circuit cartridge card carrying mechanism which is compatiblewith air cooling of the components contained on the card.

[0028] It is a still further object of the present invention to providea printed circuit board which is still nonetheless compatible with theincorporation of ancillary circuit components such as capacitors,resistors, heat sinks, and the like which extend upward from the printedcircuit board.

[0029] It is a yet another object of the present invention to provide anEMI shield spring structure which is operative as a mechanism forproviding electrical connections and EMI shielding continuity between aprinted circuit card and an EMI shield structure disposed on a printedcircuit board to which the card is also separately electricallyconnected.

[0030] It is a further object of the present invention to provide aguide mechanism on a printed circuit board for cartridge insertion so asto consume only a small space in the side-to-side direction, betweenloaded cartridges.

[0031] Lastly, but not limited hereto, it is an object of the presentinvention to provide an integrated printed circuit card cartridge andprinted circuit board mechanism which provide compactness, air-coolingcapabilities, EMI shielding, hot pluggability, and mechanical forceadvantages both for the insertion and removal of printed circuit cardsand the insertion and removal of fully populated printed circuit boards.

[0032] The recitation herein of a list of desirable objects which aremet by various embodiments of the present invention is not meant toimply or suggest that any or all of these objects are present asessential features, either individually or collectively, in the mostgeneral embodiment of the present invention or in any of its morespecific embodiments.

DESCRIPTION OF THE DRAWINGS

[0033] The subject matter which is regarded as the invention isparticularly pointed out and distinctly claimed in the concludingportion of the specification. The invention, however, both as toorganization and method of practice, together with the further objectsand advantages thereof, may best be understood by reference to thefollowing description taken in connection with the accompanying drawingsin which:

[0034]FIG. 1A is an isometric view illustrating a cartridge inaccordance with the present invention;

[0035]FIG. 1B is a side elevation view of the cartridge shown in FIG.1A;

[0036]FIG. 2 is a side elevation view of the cartridge shown in FIG. 1Bexcept with the cover removed so as to provide a view of some of theinterior components;

[0037]FIG. 3A is a side elevation view illustrating a preferred levermechanism for card insertion and removal and more particularlyillustrating lever arm positions when a card is fully inserted;

[0038]FIG. 3B is a view similar to that shown in FIG. 3A except that thelever positions shown are indicated when a card is a in the fullyremoved position;

[0039]FIG. 4 is an isometric view illustrating the combination of a topcartridge wall member together with a movable card-carrying mechanism;

[0040]FIGS. 5A through 51 illustrate a sequence of operations for theloading of a printed circuit card into the cartridge of the presentinvention;

[0041]FIG. 6 is an isometric view illustrating a cartridge of thepresent invention inserted into a single slot on a printed circuit boardwhich also conforms to the requirements of the present invention;

[0042]FIG. 7 is an isometric view similar to FIG. 6 but moreparticularly illustrating the entire printed circuit board with a singlecartridge installed;

[0043]FIG. 8 is an isometric view illustrating a detailed portion of aprinted circuit board in accordance with the present invention andparticularly illustrating a guide system as preferably employed herein;

[0044]FIG. 9 is an isometric view illustrating the bottom of a printedcircuit board in accordance with the present invention and moreparticularly illustrating a preferable mechanism for circuit boardinsertion and removal;

[0045]FIG. 10 is an isometric view illustrating (in a detailed close up)a portion of the preferable board insertion and removal mechanism asshown in FIG. 9;

[0046]FIG. 11 is an isometric view illustrating the actuation mechanismfor the drive arm shown in FIG. 9;

[0047]FIG. 12A is a side elevation, cross-sectional view illustratingthe EMI shield system of the present invention particularly with respectto the cooperation between printed circuit board shield plates,cartridge bezels, EMI shield springs, and conductive stiffenerstructures;

[0048]FIG. 12B is a simplified view of the system shown in FIG. 12Aprovided to more particularly indicate movement of the components;

[0049]FIG. 13A is a top view of the EMI shield spring employed inconjunction with the EMI system of the present invention; and

[0050]FIG. 13B is a side elevation view of the spring shown in FIG. 13A.

DETAILED DESCRIPTION OF THE INVENTION

[0051]FIG. 1A illustrates an isometric view of a preferred embodiment ofthe present invention. In particular, FIG. 1A illustrates cartridge 100which contains printed circuit card 200 (visible in FIG. 2). Cartridge100 includes front wall or bezel 130 which preferably comprises metal.Bezel 130 is pivotally attached to top wall member 120 of cartridge 100.Side cover 110 is attached to bezel 130 at points 137 and 138. Notably,side wall cover 110 includes ridge portion 111 extending along a bottomportion of wall 110. Additionally, as an additional major component,cartridge 100 includes actuating lever arm 141 which is used to insertand remove printed circuit card 200 from printed circuit boards intowhich cartridge 100 is inserted. Additional appreciation of theoperation of cartridge 100 is discernible from the side elevation viewshown in FIG. 1B which particularly illustrates pivot point 144 foractuating lever arm 141. By operation of lever arm 141, an internalmechanism (not visible in FIG. 1A or 1B) urges printed circuit card 200having edge connector 201 into corresponding mating connectors (311 inFIGS. 6, 7, and 8) on circuit board 300 whose construction is moreparticularly described below and which cooperatively interacts withcartridge 100 in several ways.

[0052] Top wall member 120 preferably comprises a polymeric materialwhich exhibits sufficient stiffness to support the operation of thelever arm mechanism which is included in preferred embodiments of thepresent invention. Top wall member 120 also preferably includesapertures 121 near the front of the cartridge and aperture 122 near theread of cartridge 100 for the passage of cooling air for thosesituations where air cooling is desirable. Top wall member 120 ispreferably formed to exhibit a generally U-shaped cross-section as amajor portion of its structure.

[0053] Side wall 110 also preferably comprises a polymeric materialwhich is substantially flat and is attachable to top wall 120 along thetop edge of wall 110 using any convenient attachment means such asscrews 176, 177, and 178 as shown in FIG. 5H which is more particularlyconsidered below. Significantly for the present invention, side wall 110includes a raised portion or ridge 111 which extends along a bottomportion of side wall 110. Ridge 111 may possess any convenientcross-section, however, a smooth-rounded cross-section is shown. Themain feature of ridge 111 is that it possesses a cross-section whichmatches the cross-section of slots 351 provided in guides 350 (see FIG.10) affixed to printed circuit board 300.

[0054] Front wall portion (or bezel) 130 is pivotally attached to topwall member 120 at pivot point 137. Front wall 130 also preferablyincludes mounting bracket 149 to which is attached actuating pivot arm141 which is used as an external drive mechanism for insertion andremoval of a printed circuit card 200 into a printed circuit boardconnector 311. Front wall 130 preferably comprises a conductive materialwhenever it is desired to provide electromagnetic interferenceshielding. However, in those circumstances in which EMI shielding is notessential or desired, front wall 130 may comprise a polymeric materialor other nonconductive material. Front wall 130 also preferably includesan opening in the front thereof through which printed circuit boardshield plate 202 is visible. In other applications of the presentinvention, front wall 130 is provided with an opening in the frontthereof so that access may be provided to various pluggable connectorsthat may be found on the front edge of a printed circuit card. Suchprinted circuit board connectors are disposed through the opening infront wall 130 and may include telephone line RJ-11 type connectors andthe like. Front wall 130 also preferably includes one or more openingsfor the inclusion of light guides 132 which are optionally provided sothat light indicators, such as LEDs found on the leading edge of printedcircuit board 300, may be viewed from external positions.

[0055] It is noted that the present invention incorporates a number offeatures that have been provided for specific purposes. For example, inthose applications in which relatively high power levels are generatedby an enclosed printed circuit card, it is desirable to provide top wall120 with apertures (121 and 122) such as those shown in FIG. 1A.However, if power dissipation is not a concern, such apertures do nothave to be present. Likewise for those situations in which connectoraccess to printed circuit card components is not necessary, front wall130 does not have to be provided with an opening. In a similar fashion,in those situation in which electromagnetic interference is not anissue, front wall 130 may comprise materials which are not electricallyconductive. In general, the nonconductive portions of cartridgesmanufactured in accordance with the present invention are preferablyformed in polymeric molding operations.

[0056] The cartridge of the present invention is particularly useful inthose situations in which it is desirable to have a relatively highcomponent packaging density. Accordingly, it is desirable that cartridge100 be shaped in as a thin a package as possible so that as manycartridges as possible may be disposed in adjacent positions.Accordingly, in preferred embodiments of the present invention, onlycover 110 on one side is provided. In such embodiments, there is onlyone ridge 111 which engages mating guides 350 on printed circuit board300. The lack of necessity for providing a ridge and cover on theopposite side of cartridge 100 is eliminated. By eliminating thisstructure, cartridge 100 may thus be made thinner. In yet anothervariation of the present invention, in those circumstances in which aplurality of cartridges are inserted in adjacent positions, as ispreferred in the present invention, cartridge 100 is provided withinterlocking mating members 112 and 113 (see FIG. 6) which serve toslidably interlock adjacent cartridges. This further contributes to thestrength and rigidity of the entire structure. This interlockingmechanism also contributes to the lack of a need for cover such as t 10to be provided on both sides of cartridge 100.

[0057]FIG. 2 is a side elevation view similar to that shown in FIG. 1Bexcept that cover 110 is removed so as to more particularly show andillustrate the internal components and the inclusion of cartridge 100.In particular, FIG. 2 shows printed circuit card 200 with its edgeconnector 201 affixed in position with respect to carrier 150. Carrier150 is a movable portion of the present invention, and it is the part ofthe mechanism shown in FIG. 4 as described below which provides adescription of a preferred mechanism for carrier 150. FIG. 2 alsoillustrates that in those embodiments of the present invention in whichair circulation is a desired factor, front wall 130 also preferablyincludes a plurality of apertures 131 which also facilitate the passageof cooling air. FIG. 2 also illustrates the fact that front wall 130also preferably includes aperture 133 on the bottom thereof (see alsoFIGS. 12A and 12B) which provides an exiting path for tab portion 203 ofEMI shield plate 202 (see FIG. 2A) which serves as part of aninterconnnected EMI shield system. The remaining portion of FIG. 2serves to particularly indicate the preferred system of linked leverarms which are employed to effect the desired motion of carrier 150 andprinted circuit card 200. The action and operation of this levermechanism is more particularly illustrated in FIGS. 3A and 3B.

[0058] A preferred system of pivoting arms for moving carrier 150 isseen in FIGS. 3A and 3B. In particular, it is noted that pivot points144 and 147 are fixed. In particular, pivot point 144 is preferablyfixed in bracket 149 which is affixed to a point on front wall 130 atthe top thereof as shown. Likewise, pivot point 147 is affixed on topwall 120. In preferred embodiments of the present invention, top wall120 comprises a polymeric material having a substantially U-shapedcross-section. As such, this provides a mechanism for extending apin-like pivoting mechanism across the U-shaped channel. Thus, mostsignificantly for the present invention, it is seen that the preferredleverage mechanism includes pivot points 144 and 147 which are fixed tofront wall 130 and top wall 120, respectively. The preferred leveringmechanism includes external actuating arm 141, as shown. Second arm 143extends from fixed pivot point 147. Connecting arm 142 linking externalarm 141 with second arm 143 is also shown. Arm 141 and arm 142 arelinked at pivot point 146. Arm 142 and arm 143 are linked at pivot point145. Also notably for the present invention, at pivot point 145 there isprovided a pin which preferably rides in a horizontal slot provided incarrier 150. The motion of the pin in the slot is the mechanismpreferably employed for imparting upward and downward motion to carrier150.

[0059] It is noted that FIG. 3A illustrates the position of the variousarms employed in preferred embodiments of the present invention whenprinted circuit card 200 is fully inserted into board connector 311.Likewise, FIG. 3B illustrates the position of a desired leveragingmechanism when card 200 is fully removed from board 300. It is alsonoted that since front wall 130 is pivotally connected to top wall 120at pivot point 137, the mechanism shown in FIGS. 3A and 3B isparticularly useful in that it permits the pivoting operation to occurby providing a longer distance between pivot point 147 and pivot point146, thus permitting extension of the configuration of the arms used forinsertion and removal during bezel pivoting.

[0060]FIG. 4 illustrates the fact that carrier 150 preferably comprisestwo principal components: tail stock component 150 a which possesses acertain degree of flexibility (as is discussed more particularly belowin reference to FIG. 5B) together with flat wall member portion 150 b.Carrier wall portion 150 b (also referred to herein using referencenumeral 152) includes guide portions 153. Guide structures 153preferably include tongue and groove-like structures which serve toguide carrier 150 in a more uniform vertical motion with respect to topwall 120. FIG. 4 also illustrates adjusting bracket 151 which includes atop portion (not visible) which rides in a toothed slot along tail stock150 a and includes a ratchetting pawl together with a release mechanismsuch as that shown in the above-referenced patent issued in the name ofone of the inventors herein. Adjusting bracket 151 therefore provides amechanism for holding various sizes of printed circuit cards in carriermechanism 150.

[0061] Attention is now directed to the sequence shown in FIGS. 5A-5I.This sequence illustrates the easy loading aspects of the presentinvention with respect to the placement of printed circuit cardstherein. A parts list for a cartridge in accordance with the presentinvention includes: (1) bezel and linkage subassembly (front wall 130,top wall 120, linkage mechanism 141-149, and carrier 150); (2) cover110, clip 154; (3) short card arm 155′; (4) long card arm 155″; and (5)eight screws (171-178).

[0062] In preferred embodiments of the present invention, printedcircuit card 200 to be inserted is a standard PCI (Personal ComputerInterface) card. However, the present invention is not limited to theutilization of these specific printed circuit cards.

[0063] The process for inserting card 200 into cartridge 100 of thepresent invention begins with a consideration of FIG. 5A. Printedcircuit card 200 is oriented as shown by loading the upper front cornerof card 200 into clip 154 and rotating card 200 so that it engages itsheel portion with slot 156. This operation is done for both short andfor long printed circuit cards. To accommodate cards which are short inheight, clip 154 is slid down until the card is held securely at clip154 and at heel 156 together. For a detailed description of appropriatesliding mechanisms for carrying out this operation, attention isdirected to the above-mentioned patent. The operation shown in FIG. 5Ais performed with front wall or bezel portion 130 rotated out of theway, as shown.

[0064] Next, as illustrated in FIG. 5B, tail stock portion 150 a ofcarrier 150 is bent down (150 a′) to allow for either short card arm155′ or long card arm 155″ to be attached to carrier 150. In particular,carrier 150 with tail stock portion 150 a is shown as 150 a′ as beingbent down in FIG. 5B. Arms 155′ and 155″ (not both present at the sametime) are provided for slideable adjustment along tail stock 150 a ofcarrier 150. In particular, in preferred embodiments of the presentinvention, these arms slide in a ratchetting toothed strip and areprovided with releasable pawl mechanisms for snugging up againstinserted printed circuit card 200. Again, attention is directed to theabove-referenced patent which is incorporated herein by reference. Toposition arm 155′ and 155″ onto a card edge, the arm is slidhorizontally. When the arm is squared to the card edge, the arms arepressed against the edge so as to engage clip or heel portions found onthe bottoms of short or long card arms 155′ or 155″.

[0065]FIG. 5C illustrates the fact that front wall or bezel 130 may alsobe temporarily removed from top wall 120 to accommodate passing tab 203on shield plate 202 of printed circuit card 200 through aperture 133provided for that purpose in the front of bezel 130. FIG. 5C alsoillustrates the relative positions of adjusting arms 155′ and 155″(short card and long card positions, respectively).

[0066]FIG. 5D illustrates several additional features of the presentinvention and further aspects of assembly. In particular, FIG. 5Dillustrates the presence of brace 136 which extends from a bottomportion of front wall 130 in a substantially diagonal direction so as tobe affixable to top wall 120 at point somewhat distal from the topportion of front wall 130. Bracket 136 preferably comprises metal. It isattached to front wall member 130 by any convenient means particularlyincluding spot welding. Bracket 136 provides additional rigidity whichis found to be at least somewhat desirable when polymeric components areemployed.

[0067] Additionally, FIG. 5D illustrates the presence of notch 139 inthe side of front wall member 130. Notch 139 is provided to permit easypassage of clip or heel 156 as front wall 130 is reattached to theassembly during loading operations for printed circuit cards. A moredetailed view of this notch is provided in FIG. 5E;

[0068] Next is considered the illustration shown in FIG. 5F. FIG. 5Fillustrates yet another aspect of the present invention. In particular,FIG. 5F illustrates the relationship between top wall member 120, frontwall or bezel 130, and moving carrier 150 which includes tail stockportion 150 a and flat plate portion 150 b. In particular, FIG. 5Fillustrates the presence of brace 136 which extends from bezel 130 totop wall member 120 to which it is ultimately attached via two screws171 and 172 (see FIG. 5G). Since one of the objects of the invention isto provide as thin a profile as possible, while still preservingstructural rigidity, it is seen that carrier plate portion 150 b alsopreferably includes recess 157. The presence of recess 157 permits brace136 to be mounted in corresponding recess 129 in top wall channelsupport 120 using screws 171 and 172 as shown in FIG. 5G. Additionally,it is seen that top wall 120 and movable carrier 150 both include matingslidable portions 153 which provide improved guidance to more readilyensure vertical motion as lever 141 is actuated. Tongue and groovestructures are employed to provide suitably mated sliding portions. Itis also seen in FIG. 5F and in FIG. 5G that front wall or bezel 130includes notch 139 which is provided for ease of assembly and, inparticular, for ease in passage of clip 156 (see FIG. 5A).

[0069] In addition to the features shown above, it is seen that FIG. 5Gindicates the presence and utilization of adjustable arm 155′. Inparticular, the particular form of the adjustable arm shown in FIG. 5Gis that which is used to support short printed circuit cards.Additionally, it is seen that FIG. 5G illustrates the presence of tab204 which is preferably present on the top of EMI shield plate 202 whichis attached to printed circuit card 200 (see also FIGS. 5H and 5I). Inparticular, this tab preferably includes stamped or pressed prongs whichslide against the interior front wall portion of bezel 130 to providecontinuous electrical contact for purposes of providing continuous EMIshielding as lever 141 is actuated to move carrier 150 and board 200into position. It is also noted that, as this motion takes place due tothe actuation of lever 141, EMI shield plate 202 also moves downward soas to move tab 203 through opening 133 in bezel 130 (see FIG. 12B).

[0070]FIG. 5H illustrates a final assembly operation for a cartridge inaccordance with the present invention. In particular, it is seen thatcover 110 is slid into position and is fastened to top wall member 120using screws 176, 177, and 178, as shown. Lastly, front wall member 130is pivoted into final position and affixed to the assembly via screws174 and 175, as shown. The completed assembly is shown in FIG. 51 inisometric view.

[0071] Having described cartridges for carrying printed circuit cards,attention is now directed to the printed circuit board intended for usein conjunction with the cartridges of the present invention. Inparticular, FIG. 6 illustrates cartridge 100 fully inserted into printedcircuit board 300. In particular, it is noted that ridge 111 on cover110 slidably engages grooves or slots 351 in guides 350 which areaffixed to printed circuit board 300 through openings in stiffener 330.It is also noted that cartridge 100 preferably includes interlockingmechanisms 112 and 113. If a cartridge in accordance with the presentinvention were to be inserted in the slot just to the right of theoccupied slot in FIG. 6, its mating interlocking portion 113 wouldengage the corresponding mating interlocking portion 112 on thecartridge that is already shown. In this fashion when a plurality ofcartridges are inserted into a printed circuit board in accordance withthe present invention, there is formed an interlocking structure whichprovides enhanced strength, rigidity, and alignment characteristics.

[0072]FIG. 6 also illustrates the presence of a parallel row ofapertures 331 and 332 present in stiffener 330. These aperturesaccommodate the easy insertion of EMI spring shield member 500 which ismore particularly described below (see FIGS. 13A and 13B). It is EMIshield spring 500 which is engaged by tab portion 203 of EMI shieldplate 202. Tab 203 is deployed downwardly through opening 133 in bezel130 to provide continuous EMI shielding between card 200 and stiffener330 which preferably comprises a conductive material such as metal whenemployed for EMI shielding purposes.

[0073] Attention is next directed to the apparatus shown in FIG. 7. FIG.7 illustrates a number of the cooperating subsystems of the presentinvention. As with FIG. 6, it illustrates the cooperative interactionbetween cartridge 100 and printed circuit board 300 particularly withrespect to guides 350 present on board 300. Guides 350 also includeoptional alignment tabs 353 which serve as helpful guides duringcartridge insertion. In operation of the systems of the presentinvention, cartridge 100 is aligned with slots or grooves 351 (see FIG.8) in guides 350 and is inserted so as to occupy the position as shownin FIG. 7. At this point, lever arm 141 is actuated, preferably by alifting motion, which causes internally disposed carrier 150 to movedownward and to thereby insert card edge connector 201 intocorresponding printed circuit board connector 311. During actuation oflever arm 141, plate 202 with tab 203 is moved likewise downward so thattab 203 makes contact with EMI spring shield 500 which is already incontact with stiffener 330.

[0074]FIG. 7 also shows the preferable positioning for board insertionand removal mechanism 400, or at least so much of that system as isvisible in FIG. 7. Additional aspects of board removal system 400 aremore particularly described below. However, spur gear 411 and toothedarm 420 (see FIG. 11) are nonetheless visible in FIG. 7.

[0075]FIG. 7 also indicates the inclusion of rear board edge connector340 disposed on the back edge of board 300. Also discernible in FIG. 7is the preferred structure of the present invention in terms of theprinted circuit board assembly itself. In particular, it is seen thatboard 300 includes insulative base 320, printed circuit subboard 310,and stiffener 330. Stiffener 330 preferably comprises metal whenemployed for EMI shielding purposes. However, in those embodiments ofthe present invention in which EMI shielding is not a factor,nonconductive materials may be employed in the fabrication of stiffener330. However, in preferred embodiments of the present inventionstiffener 330 preferably comprises a single stamped and formed sheet ofmetal.

[0076] As an additional observation with respect to FIG. 7, it is seenthat, as is often the case with printed circuit board structures,certain circuit components extend upwards from its surface. Accordingly,it is seen that stiffener 330 may include selective apertures thereinfor the passage of components, such as capacitors 342 and/or heat sinks341. Those skilled in the electronic arts will readily appreciate thatother components may be employed and may be positioned in differentplaces with respect to stiffener 330.

[0077]FIG. 8 provides a more detailed view of some of the structuresseen in FIG. 7. In particular, it is seen that circuit board connectors311 are disposed between rows of board level guides 350. In preferredembodiments of the present invention, guides 350 are formed from anintegral polymeric structure as is readily fabricated in a moldingoperation.

[0078] Attention is next directed to the description of the mechanismemployed in the present invention for the insertion and removal ofentire circuit board 300 together with any cartridges 100 which may beinserted into and connected with the board. Preferred embodiments ofthis mechanism include rigid driving arm 420 with toothed portion 419which is driven by spur gear 411 (see FIG. 11) which is affixed to plate412 which in turn is attached to a formed portion of stiffener 330 (seenin greater detail in FIG. 11). Spur gear 411 preferably includes centralhexagonal opening 413 for the insertion of an Allen wrench which causesrotation of gear 411 which moves drive arm 420 inwardly and outwardly ina recessed groove portion of base support member 320. There ispreferably provided at least one lever arm attached to drive arm 420. Inpreferred embodiments of the present invention, two lever arms areprovided. These lever arms, 421 a and 421 b, are seen in FIGS. 9 and 10.Lever arms 421 a and 421 b are pivotally attached to drive arm 420 atpin or rivet 422. Lever arms 421 a and 421 b also include pins 423 a and423 b respectively as best seen in FIG. 10. These pins ride in slots 360a and 360 b respectively formed in base support member 320.

[0079] In what is best as described as a “back stroke motion,” as drivearm 420 is driven inwardly, drive arm 420 together with lever arms 421 aand 421 b change configuration from a “Y” configuration as seen in FIG.10 to a “T” configuration as illustrated in FIG. 9. As the configurationof these arms changes, edges of arms 421 a and 421 b push against pinsfound on the enclosure or frame into which the board is inserted. Thesepins are located externally to the printed circuit board shown but arepresent at corresponding positions 430 a and 430 b on circuit board 300.It is these positions which correspond to the pin positions on theexternal enclosure. Likewise, during removal operations, the other edgesof arms 421 a and 421 b press against horizontally mounted external pinsfound in slots 435 a and 435 b, respectively. These slots are present inbase support member 320. However, the pins which lie in these slots arein fact part of the enclosing apparatus or the frame into which thecircuit board assembly is inserted. In this way, through a “reverse backstroke” operation, the entire board assembly is easily removed from thesystem into which it is connected.

[0080]FIG. 11 is also useful for illustrating part of the EMI shieldingsystem of the present invention. In particular, FIG. 11 shows theinclusion of EMI spring shield 500 which is shaped to be readilyinserted into apertures 331 and 332 in stiffener 330. In particular,aperture 331 includes a forward edge which engages a forwardly facingslot or pocket (reference numeral 502 in FIG. 13B). Accordingly, shield500 includes an edge which is in firm electrical contact with stiffener300. The other edge of shield 500 includes a flexible portion 501 whichextends through aperture 332. The leading edge portion of shield spring500 includes peak 504 which electrically contacts bezel 130 duringcartridge insertion (see FIG. 12A). FIG. 12A illustrates the insertionan edge of aperture 331 into slot or pocket 502 in spring shield 500.FIG. 12A also illustrates the presence of printed circuit card shieldplate 202 in its fully downward position extending through aperture 133in bezel 130. In doing so, tab 203 on plate 202 also electricallyengages a portion of shield spring 500. In particular, tab 203 engagesedge 507 seen in FIG. 13A.

[0081]FIGS. 13A and 13B provide a detailed description of the structureof EMI shield spring 500. This spring shield preferably comprises asingle sheet of stamped metal which is formed as shown. Preferablematerials for this shield spring include beryllium copper ½ hard with analternate of stainless steel ½ hard. FIG. 13A provides a top view of thedesired structure, and FIG. 13B provides an end view. There areapertures in spring shield 500 between edges 505 and 507. It is throughthese apertures that tab 203 is disposed so as to contact edge 507.Region 509 is a tab region of the structure as is region 501. Top orpeak 504 engages the bottom portion of bezel 130. Also of note is thepresence of pocket or slot 502 which engages an edge of aperture 331 instiffener 330. In particular, it is noted that as stamped shield 500preferably includes prongs 503 which are formed by the stampingoperation employed in the manufacture of the shield spring. Prong 503 isalso employed to provide improved electrical contact between shield 500and stiffener 330. It is further noted that FIG. 13B is particularlyuseful in that it identifies a plurality of surfaces or edges that arealso visible in FIG. 13A. Correspondingly numbered parts are shown inthese two figures.

[0082] From the above, it is seen that the present application describesan interrelated system of structures and devices all of which are aimedat providing tightly packed, dense, well-shielded printed circuit boardand cartridge structures which renders it possible to insert and removeentire printed circuit boards even when fully populated by printedcircuit cards. In particular, it is seen that the printed circuit cardcartridges of the present invention provide a cooperative housing andinsertion structure for board level guides and which also incorporate anintegrated EMI shield system which is fully operative before, during,and after card insertion. It is further seen that the system of thepresent invention includes a relatively stiff printed circuit boardwhich is capable of sustaining insertion and removal forces even whenfully populated with electronic printed circuit card components.

[0083] It is also seen that the present invention includes structureswhich provide continuous EMI shielding which mates with and matchesshielding from a printed circuit card to corresponding EMI shieldstructures found on the printed circuit board itself. It is also seenthat the cartridge preferably employed in the present invention includespivotably mounted components which make printed circuit card insertionrelatively easy. Lastly, but not limited hereto, it is seen that thesystem and apparatus described in the present application fulfills,either individually or collectively, in its various embodiments, all ofthe objectives set forth above though not necessarily all of themsimultaneously.

[0084] While the invention has been described in detail herein inaccordance with certain preferred embodiments thereof, manymodifications and changes therein may be effected by those skilled inthe art. Accordingly, it is intended by the appended claims to cover allsuch modifications and changes as fall within the true spirit and scopeof the invention.

What is claimed is:
 1. A board level EMI shield system comprising: aprinted circuit board; a conductive stiffener disposed on said printedcircuit board, said stiffener also being coextensive with at least aportion of said printed circuit board with a portion of said stiffenerextending beyond an edge of said printed circuit board with saidextended portion including two rows of parallel slots; at least one EMIshield strip disposed so as to have a portion thereof engaging the edgesof said slots with another portion thereof extending through a slot inthe opposing parallel row of slots.
 2. The system of claim 1 furtherincluding a printed circuit card cartridge which is electricallyconnected to circuits on said printed circuit board and which includes aconductive bezel which houses a conductive EMI shield plate attached tosaid printed circuit card, said shield plate including a tab whichelectrically engages said shield strip portion which extends throughsaid slot in said parallel row of slots.
 3. The system of claim 2further including an electrically conductive link between said bezel andsaid circuit card EMI shield plate.